The issue
is the disk header cannot be overwritten by the oracleasm command which is
written by the previous commands. For this you have to manually overwrite the
header information by the OS dd command.

Step 1:
find out the device information using blkid command.

[dev]# blkid |grep oracleasm

/dev/mapper/mpathf1: LABEL="OCR_VOTE" TYPE="oracleasm"

Step 2:
overwrite the header with null value using dd command. Or we can say clear the
device header manually